Multiple-voltage system of motor control.



No. 874,990. PATENTED DEC. 31, 1907.

W. H. POWELL. MULTIPLE VOLTAGE SYSTEM OF MOTOR CONTROL.

APPLIGATION FILED OCT. 19, 1905.

W 15.1 WE} W Mllz'am Jf-Powel l g v BY W I TTDRNET tage Systemso UNiTED STATES. m m oFFIcE;

WILLIAM n POWELL, or Nfoawoon, 01110, assienoa TO THE BULLOCK ELECTRIC MANUFACTURING coMPANY, A CORPORATION OF omo.

mmnn-vom'aon srs'rnn or moron common.

Specification of Letters Patent. Application and 0mm 19. 1905. am No. 288.636.

Patented Dec. 31, 1907.

To all whom it my concern:

v Be it known that 1, WILLIAM H. PowaLL, citizen of the United States, residing at Norwood, in the county of Hamilton and State of Ohio, have invented certain new and useful Im rovements in Multiple-Voli Motor Control, of which the following is a full, clear, and exact specification.

My invention relates to controllers for electric motors and more particularly to controllers adapted to vary the speed of a motor by changing the voltage a plied thereto and operated from a multipl d volta e system.

n the most modernshops of all descriptions it has become the practice to employ independent electric motors for driving the various machine tools or other driven mechanisms. In connection with this class of work a wide variation of speed control is desirable and the object of my invention is to provide means for lessening the strain upon the motor and upon the gearing connecting the motor and the driven machine, upon change of speed due to the change of voltage at the armature terminals, and to roduce a gradual change in speed in passing rom one step to the next.

By my invention, a multiple voltage system is used, and I provide automatic means for controlling the insertion and cutting out of an auxiliary field winding. On

each increase in otential at the terminals of the motor, which is normally a shunt motor, an auxiliary field winding is inserted in the circuit so that, the motor will not suddenl come up to the speed corresponding to that voltage. In the preferred form of my invention, herein illustrated and described, the auxiliary field winding is a seriesv winding andis inserted inseries with the armature winding. This series winding is afterwards automatically short circuited or removed from the armature circuit and a predetermined interval of time is caused to elapse before this winding is cut out, such interval bf time being of sufficient duration to allow the motor to speed up -to some 'windin extent. U' on cutting out the series field a ther increas of s eed occurs which %rings the armature to t e speed of the next running ste Further features 0 f nected to contact fingers b and 14, which fingers are a apted to be enmy invention be disclosed in the following specification and accompanying drawing and the novelty thereo w ll definitely set forth the appended claims. eference is had to the accom anying drawing which shows a diagram of my invention.

A portion of a multi le volta e distributing system is shown ag 1, 2 an 3 which is connected by a switch A to the three wire 'mains 4, 5 and 6 for supplying the motor with current at voltages which differ from each other; for examp e between the mains 4 and 5 there may be 90 volts, between mains Sand 6 160 volts, and between mains ed of a 4 and 6, 250'volts.

The armature of the motor, the spe which is to be varied, is indicated at 7 and its main field'winding at 8 connected in series with a variable field resistance 9. Themain field winding 8 and its resistance 9 are connected across the mains 4 and 6 by conductors 10 and 11 so as to receive the full voltage 2 of the system. 'An auxiliary field winding is shown at 12. This field winding'is conconductors 13 gaged by suitable contact segments on-the controller drum in such a manner that the winding will be connected in' series with the motor armature for a short space of time on a chan e of voltage at the armature terminal, 1

as will e explained later. A switch 15 having contacts 16 and 17 connected res ectively to the conductors 13 and 14, s ort circuits the auxiliary winding when the switch is closed. The bridging member of this switch is attached to the soft iron core 18 of the solenoid 19. To the lower extension ofsaid bridging members of the switch isconnected a plunger 20 which works in the cylinder .21 forming a dash-pot, The plunger 20 is provided with one or more opemngs 22 and carries a loosely fitting disk or ringr23 which normally closes the opening 22. he cylinder 21 is provided with. one or more openings 24 located at suitable distances from the closed top and bottom of the cylinder. When -current passes in coil .19 the switch is raised with a comparatively slow movement, as the air passes to the bottom of the plunger only by leakage around the same. Just before the switch is closed however the plunger passes beyond the holes 24-, permit ting aefree flow of air below it and the switch is then closed with a sudden movement.'

' hen no current asses in coil 19, the switch quickly falls due either to the force of gravity 2 spring pressure against the movab e part, as preferred, the air from the lunger passing freely through the holes 22 t e disk or ring being then raised from its seat.

The p'arts above described are interconnected and also connected to the controller fin ers 1", 1 1 1 as shown. The contrro ler .cylin er or drum is provided with a large number of contacts 25, which contacts control the connections to the armature. The controller cylinder is also provided with a metallic drum 26 suitably notched and recessed, forming contacts which control the resistance in circuit vwith the main field winding 8. As the cylinder is revolved from the off position designated 0, the fingers 1, 1 1 take the successive positions indicr ted by the dot and dash lines 2, 2', 2, 2' for forward rotation and the positions 3,

3", 3, 3 for backward rotation ofthe motor. In tracing the circuits, the switch 15 will be considered to be closed, as such is its ultimate position. Should the switch be open, the current will flow through the leads 13 and 14 and the series field winding 12 instead of going through the switch 15.

For position 2" the path of the current is as follows: from-main 5, contact finger 1, contact 27, contact 28, finger 1, switch -15, finger 1*, contact 29, contact 30, finger 1,

motor armature 7,finger 1, contact 31, contact 32, finger 1 to main 4, thus subjecting the armature in the lowest voltage of the system across the mains 4, 5. For position 2,.the field connections are from main 6, field 8, conductor 10, finger 1, drum 26, finger 1 conductor 11, to main 4, thus subjecting the field to the full voltage of the s stem, with all the resistance 9 cut out.

onnection is also made through solenoid coil 19 as follows: main 5, conductor 33, solenoid coil 19, conductor 34, contact finger 1,-

drum 26, contact finger 1 conductor 11, main 4. Coil 19 is therefore subjected to the voltage across the mains 5 and 4 and switch 15 is caused to close.-

For the osition 2 finger 1 is cut out of contact wit drum 26 and one section of the variable resistance 9 is inserted in the main field circuit of the motor, the field current passing from the field winding 8 through a section of the resistance 9 to contact finger 1 and'then to drum 26. No other changes take place, and by this weakening the main field ofthe motor an increased speed is obtained. In the same way for position 2 a still further weake of the field takes place by inserting anot er section of resistance 9in the field circuit and in this position current-passes from the field 8 through two sections of resistance 9 to finger 1 and to drum 26.

For position 2 the armature connections are from main 6, to contact fin er 1", contact 35, contact 36, finger 1, switc 15, finger 1', contact 37, contact 38, finger 1, motor armature 7, finger 1, contact39, contact 40, finger 1, to main 5. The motor armature is therefore'subjected to the volta e across the mains 6, 5 which is greater than the voltage across the mains 5, 4 across which latter mains the motor armature was connected in previous positions. The field connections and those of coil 19 are the same for this position as for position 2 and the speed of the motor is increased by the increasein voltage applied to the armature. For positions 2 and 2 the only changes that take place are the weakening of the field by cutting in sections of resistance 9 as in positions 2 and 2.

5 For position 2 the armature connections are from main 6, fingenl", contact 41, contact 42, finger 1, switch 15, finger 1, contact 43, contact 44, finger 1, motor armature 7, finger 1, contact 45, contact 46, finger 1 to main 4. The motor armature is therefore subjected .to the greatest voltage of the system.-' The field connections and those of coil 19, are the same for position 2'v as for positions 2", 2 the resistance 9 bein cut out, and increased speed is obtained by the increase in the voltage applied to the terminals of the motor armature.

For positions 2 ,252, 2" and 2 the connections remain the same except that sections of resistance 9 are successively cut into the circuit of the field winding 8 until it is all in circuit, in this manner successively weakening the field for increases in speed from positions 2 to 2 It will be noted that in sition 2 to 2 and from 2 to 2, at which times the change in voltage a plied to the motor armature takes place, nected to the solenoid coil 19 is momentaril cut out of contact with the drum 26 and circuit through coil 19 is broken. At the instant finger 1 breaks contact with drum 26, switch 15 drops and the auxiliary field winding 12 is inserted in series with the armature 7 of the passing from poger 1 conmotor, so that by the time that the increased voltage is applied to the armature, there is an increase eld, which increases the counter electro-motive force and revents a too sudden rush. of current throng the armature the speed of the motor.

- Assume that the motor is operate onaccount of the slow u ward movement of the switch, the motor wi have had sufiicient time to increase in speed before the switch is closed. 7 When the controller is moved from oil position to the startin position 2 the switch 15 is closed in tlie same slow manner.

There is as great or a reater danger of injury to the gear teeth w en the speed of the motor is decreased as when the speed is increased,'for two reasons ;first because the o erator usually throws the controller hand e to the off position' quickly, thus bringing the motor toa sudden stop; and second, on account of thegenerator action of the motor when the potential at the armature terminals is decreased, which tends to suddenly reduce The result is that the motor tends to stop more uickly than themachine or tool to which te motor is eared, causing a hammer-blow which is iable to stri the teeth ofi the gears. The insertion of t e series Winding 12 into the armature circuit tends to reduce the generator action on a decrease in. the potential at the armature terminals, as will now be ex lained. at the speed corresponding to the position 2*, with t e armature terminals connected across the 250 voltmalns. The counter electromotive.

force is less than 250 volts, say 240 volts. If the voltage at the armature terminals is decreased to 160 volts, tie. the voltage of the mains 65, the counter electromotive force will be greater for a short space of timethan the impressed electromotive force and the current in the armature and-series field will for this space of time be reversed. The result is that there will bea differential field action. The currents in the field windings and 12 will be opposite directions causmg for the moment a very weak field, which reduces to a minimunphe enerator action.

For reverse rotation of t e motor the fingers are in positions 3* to 3 successively. For

position 3 the currentpasses from main 5, finger 1,'.contact 47, contact 48, finger 1, swltch 15, finger 1 contact 49, contact50, finger 1 motor armature 7, finger 1 contact 51, contact 52, finger i to main 4. The

" armature 7 is therefore subjected to the voltage across the mains 5 and 4 and the armature current is reversed whilet'helfield'is the same as for position 2. The direction of rotation of the motor is therefore reversed and the motor operates at its slowest speed. Forpositions 3* and 3 the strength of the main field 8 is weakened as before by cutting in the sections of resistance 9. Forposition 3 the circuit'is as follows: main 6, finger 1 contact 53, contact 54, finger 1, switch 15, finger 1 contact'55, contact 56,-finger 1 motor armature 7, finger 1, contact 57, contact I as 58, finger 1, and main5. For this position, although the motor has its full field strength due to field winding 8 as in positionii" an increased speed is obtained for the reason that the armature is subjected to the increased voltage acrossthe mains 6, 5. a In positions 3 and 3 increased speeds are obtained by weakeniag the strength of the main field, by

adding sections of resistance 9. For positions 3' the connections are asfollows: main 6, fin er 1, contact 59, contact 60, finger 1 switc 15, finger 1 contact 61, contact 62, finger 1, motor armature 7, finger 1 contact. 63, contact 64, finger 1 and main 4. The motor is in this case subjected'to the greatest voltage of the system. At positions 3*? and 3 the'strength of field 8 is weakened by cutting in sections of theresistance .9. In passing between positions 3 and 3 and between 3) and 3 the auxiliary field winding'12 is cut into circuit with the armature, to'relieve the strain on the motor as already exp ained with reference to passing between positions 2 and" 2 and between 2 and 2 and is cut out again after a predetermined time. The auxlhary field winding also remains-in circuit for a pre determined time after the controller is moved frorrg sition 0 to position 3.

It is seen that I have a compound wound 1 motor, the shunt field winding only of whichis normall in circuit, and the series field winding 0 which is automatically out lnto circuit on a change of voltage, and again out out of circuit after a predetermined lnterv-al of time has elapsed. It is therefore evident from the above description that twelve speeds forward and nine speeds in the reverse direction are obtainable. 1

Although I have described a specific embodiment of myinvention it is evident that various modifications'may be .made therein without departing from the scope claims.

a What I claim as new-anddesire to secure by Letters Patent is I 1, In combination, a motor having an ar-' mature and field, means for increasing the voltage at the armature terminals, andmeans for simultaneously increasing) the effective field windings of the motor eyond what-they of the 'were just prior to making such increase in voltage.

r '2. In a system of control for electric motors, means for changing the potential at the motor armature terminals, means for simultaneously changing. the normal field strength Y of the motor, and means for automatically restoring the field strength to its previous normal condition after a predetermined interval of time.

3. In combination, a motor having an ar- 'mature, a main fieldwinding and an auxiliary field winding, means for effecting changes in the potential on the leads of the armature circuit, means for cutting the auxiliary. field winding into the motor circuit on a change of potential and an automatic time device for cutting said auxiliary field winding out of circuit. i

4. In a switch for dynamo-electric machinery, the combination with a motor, field and armature circuits therefor, an auxilia field winding, means for efiecting a change in potential on the leads of the armature circuit,

means for cutting said auxiliary winding into circuit, and an automatic time device for cutting the auxiliary winding out of circuit.

5. In a switch for dynamo-electric machinery, the combination with a motor, a main field winding and armature, circuits therefor, an auxiliary field winding, means for changing the resistance of the main field circuit and. for changing the potential at the armature terminals for efiectingvcha'nges in the s eed of the motor, means for cutting the auxi 'ary field winding into circuit on a change of potential at the armature terminals, and an automatic time device for. cutting the auxiliary field winding out of circuit.

6. In a multiple voltage system of control,

the combination with a motor, circuits theretia on the leads of the armature clrcuit, means for simultaneously increasingthe field strength of the motor, automatic means for decreasing the field strength of the motor, and means for delaying the action. of the automatic means.

7. In a multiple voltage system, the combination with a motor, circuits therefor, an auxiliary field windin means for effecting changes in the {potential on the leads of the armature circuit, means for simultaneously cutting said auxiliary winding into circuit, automatic means for cutting. the auxiliary field winding out of circuit, and a dash-pot for controlling the action of the automatic means.

8. In a multiple voltage system, the combination with a motor having an armature and a. main field, an auxilia series field winding normally out of circuit, means for eflectin a change in the potential on the leads 0 the armature circuit, means for cutting the auxiliary field winding into the armature circuit, automatic means for cutting the automatic means.

9. The combination of a multiple voltage system, a motor having a field-windin in its armature circuit, a shunt about the old winding, an electro magnetically I operated switch in the shunt circuit, a contro erand fori means for effecting changes in the potenthe auxiliary winding out of the armature circuit, and means for delaying the action of 874,990 s, g a

mally tends to open, electro-magnetic means for controlling said switch, a controller and connecting leads, said controller ha contacts adapted to vary the voltage apphed to the armature circuit, and to open .and close the circuit of said electro-magnetic means upon changing the voltage of the armature circuit.

11. The combination of a multi le voltage system, a motor having a main fie d winding and an auxiliary field winding, a shunt about the auxiliary. field windin a switch in said shunt which normally ten to open, electromagnetic means for closing said switch, means for retarding the closing of the switch, a controller and connecting leads, said controller having contacts adapted to vary the Y tem for operating said motor at d' erent speeds, means for-chan g the armature connections to said distributing system for changes in voltage,\ and means for cutting into circuit on changing the armature connections a series fie winding not in circuit immediately before said change.

1 14. In combination, a compound wound motor, a multiple voltage distributin system for operating the motor at erent s eeds, means for changing the voltage ap ied to the armature terminals, and means For automatically cutting the series field windin into circuit on a change in voltage.

15. n combination, a com ound wound,

motor, multiple voltage distn uting mains for operatin the motor at different s eeds, means for c anging the voltage apphed to the armature terminals means for simultaneously cutting the sense winding into circuit, and a time limit device for cutting the series winding out of circuit.

16. In combination, a compound wound motor, multiple voltage mains for operating the motor at different s means for changing the voltage app ied to the armature circuit, means for simultaneously cutting the series'windin into circuit, and for cuttin the series win out of circuit after a pre etermined int'erva of time.

17.. In combination, a motor having a shunt and a series field winding, the shunt winding only being normally in' circuit, means for changing the voltage apphed to the armature terminals, means for automatthe series circuit l voltage; and for cuttin the eterarmatnre and field, and means for changin the voltage at the armature terminals and i for varying the field strength at a predetermined time after the changeof voltage is 18. In combination, a compound-wound made;

motor, and controlling means for chan 7 'ng 21; In a system of control for electric m0 the voltage impressed on the armatureo the tors, means for changing the potential at motor, for cutting the series field winding of l the motor armature terminals, and means the motor into circuit as sa'd chan e in volfor automatically varying the motor field tage is made, and for leaving sai winding l strength at a predetermined time after said in circuit for a. predetermined time. i change of potential is made.

19. In combination, a compound-wound I In testimony whereof I affix my signature, motor, and controlling mechanism for changin the presence of two witnesses.

1 ing the voltafge impressed on the armature WILLIAM H POWELL ically cutting on a change of said winding out of circuit after a pr mined interval of time has elapsed.

thereof and or cutting out the series field E windin thereof at a predetermined time af- E Witnesses:

& FRED J. KINSEY,

ter sai change in voltage is made AIrrnUR F. KEVIS.

20. In combination, a motor having an 

